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HENRY M. s'roW, or SAN FRANCISCO, CALIFORNIA.

Lettere .Patent No. 75,708, datedvMarcz. 17, 1868.

- IMPaeveD WELL-DRILL.

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TO ALL WHOM I'l MAY G'ONERN:

Be it known that I, HENRY M. STOW, of San Francisco, in the county of San Francisco, and State of California, have invented a new and useful Improvement in Drills for Boring Artesian Wells; and I do hereby declare that the following is a full, clear, and exact description thereof, reference bingrhad to the accompanying drawings, and to the letters of reference marked thereon, in which- Figure 1 is a vertical section of the drill and drill-stock, the two parts B and B ot' the drill-stock being closed together, and the movablev cutters thrown out. v

Figure 2 is a `sirnilarvsection, Athe said two parts Vof thev drill-stock being drawn asunder, and the movable cutters'pushed in; and l- Figure 3 is a cross-section in line a: ai, fig. 1. v

Theobject of this invention is to provide a drill that will form a hole large enough to admit of putting down a pipe of uniform diameteras Vthe well is bored, through which the drill may be withdrawn and re-inserted without removing the pipe.

It often happens in boring artesian wells that some of the strata penetrated areso loose and friable that the well will cave in during the process of drilling, unless the walls are protected by a curb-pipe; but in boring with the ordinary drill, if'a'pipeis inserted above. the drill, the latter cannot lbe withdrawn and re-inserted without removing the pipe. AI obviate this diliieulty by means of movable cutters, located in the drill-stock, above the drill proper, which will slip inwardly so as to pass through a hole smaller than that actually bored when the drill is withdrawn from the well, but which, when the drill is again inserted, -will strike out radially on the ii'rst fall ofthe drill, and so remain while the drill is werking, that they will form a hole somewhat larger than is `necessary to draw the drill and movable cutters through. v

In the accompanying drawings, A is an ordinaryvdrill, and B is the lower part of the drill-stock, into which the drill A is inserted. This part of'the stock is cylindrical in form, and about the size of .the hole which the drill A will bore, Bis the upper portion of the drill-stock, also cylindrical in form, and nearly aslarge as the part B, and is connected thereto by means ot' sliding tenons I) b, fitting into corresponding vertical mortisesin B. C and C are movablecutters for enlarging the hole formed by the drill A,Iand (Z is a central guide-rod,- irmly attached at'its lower end to B, but sliding in a central hole in B.

It will be seen that the lower ends of the tenons b Z1 are made in wedge-form by bevelling their inner sides; The cutters C and C move freely in and out radially in mortises in the part, B, ofthe cylindrical stock. It will be seen also that when the part, B', is pressed down so as to be in close contact with the part B, as shown in fig. 1, the wedge-shaped lower ends ofthe tenons i; I), acting upon the rearends ofthe cutters C andfC, will throw them out, as. shown in g. 1, but when B and 'B/ are drawn asunder, as shown in tig. 2, the said cutters, being bevelled on their upper corners, will freely slip inward on coming in contact with the pipe or any other obstruction in their ascent. v i

'lhe parts B and B should adhere together with such tenacity that they will never separate except when the movable cutters encounter some obstruction in-their ascent, so that in working the drill, the said two parts will risc and fall together, and only separate when'the whole apparatus is withdrawn from the well. A suicient degree of tenacity for this purposemay be obtained by mere friction ofthe moving parts connecting B and B". A slotor recess in the centre rod d, embracing a stop-screw, @prevents the parts B and B from becoming detached, or from separating further than shown in fig. 2. The said stop-screwne may press against the rod d so as to create the necessary friction to prevent the parts B anfd B from separating in the ordinary working of the drill. When the drill is inserted in the well, (after having been withdrawn therefrom,) the parts B and B are separated, as shown in fig. 2, and the movable cutters pushed in, so that they will pass. freely down through the curb-pipe; but when the drill A strikes the bottom, the superineumbent weight ofthe drill-rods and sinker will cause the said parts B and Bl to close together, the wedge-shaped tenons throwing out the movable cutters, as shown in iig. 1. I

The movable cutters may have a bolt running transversely through B, and through slotsf in the cutters, i

but this is not absolutely essential, es they will necessarily remain in place when in the well. There may be two, three, or four movable cutters, and a, corresponding number of wedge-shaped tenons, but it will be most convenientjo have three cutters, two on une side and one on the other, working between them.

What claim as my invention, and desire to secure by Letters Patent, is

In combination with a. drill-stock in two parte, as described, movable cutters, oper-ited by wedge-shaped tenons to enlarge the hole formed by the drill, substantially as shown and described.

HENRY M. STOW. Witnesses:

J. J. CooMBs, Jos. L..CooMBs. 

